I was just going to post a question about ants in my house, but I"ll reply to your ants in the garden as well
I have found ants don't like to be disturbed, so whenever I find an ant colony outside where I don't want one (in my flower pots, next to the garden... you name it, they're everywhere around here...), I just mess it up often and they quickly move on. I haven't had a problem with red/orange ants, but we have little black ants everywhere. I would assume they'd behave similarly, but who knows. So I guess if I had ants in my garden, I would just keep messing up (step on it, poke sticks into it...) the top of their colony and hope they quickly move elsewhere. Oh, and try not to get bitten in the process
I know ants are attracted to sweetness, so if you have any aphids on your plants, they might be interested in the sweetness left on your plants by aphid secretions, but generally, I don't think the ants will bother your plants much other than they might start to eat your ripe fruits.
Good luck.
